Find every subdomain
of a domain.

Every hostname under a domain that ever appeared in a public TLS certificate — with certificate counts, first/last seen and live DNS status.

1 host · 191 ms

HostCertsFirst seenLast seenDNS
*.today.yahoo.com 14 2026-06-23 2026-09-29 —

Programmatic access, with DNS A records: API GET /v1/hosts/today.yahoo.com (API key for paging).

Shown here: hostnames with a certificate that is valid now or expired within the last 90 days. The full history since 2013 — hostnames whose last certificate expired earlier — is a Pro plan method: GET /v1/hosts-history/today.yahoo.com.